-LRB- CNN -RRB- -- George Zimmerman should only be prosecuted if , after an exhaustive investigation and an honest assessment of Florida 's `` stand your ground '' law , special prosecutor Angela Corey concludes that there is a strong possibility of proving his guilt at trial for the killing of Trayvon Martin .

No American should ever be prosecuted for any crime as a consequence of the demands of a crowd , however large or vocal . This core principle of justice should stand regardless of the facts of a case or the radioactivity of a defendant . The justice system , fragile at best , is imperiled when prosecutorial decisions are tied to politics .

That said , good prosecutors should vigorously pursue cases when justice demands , even and maybe especially , when there are legal impediments . To do less , especially in a homicide case , is to create one of society 's greatest miscarriages : the failure to hold accountable someone who acted culpably to take the life of another . The victim 's life must be vindicated . Unfortunately , some prosecutors find themselves legally paralyzed by complex cases or shrink from pursuing matters that are not air tight .

Unless there are clear legal red lights at the outset , successful prosecution frequently means stretching existing laws to achieve just ends . This means arguing at trial , and on appeal , that someone like Zimmerman can be brought to justice notwithstanding Florida 's strong self defense law , or that the law should be construed less favorably to those who resort to deadly force .

In many self defense cases , the defendant can and does argue that the case should revolve around the uncertain moments of terror faced when he was confronted by an assailant , and that everyone in the court room is after-the-fact quarterbacking . The outcome of cases is determined by comparing the defendant 's actions against state law . In no part of the country is a person threatened with death or serious physical injury required to suffer the first blow . A person can be found to have acted justifiably and reasonably for killing an unarmed person depending on the circumstances .

Opinion : Without protests , justice for Trayvon Martin ca n't be served

Florida authorizes deadly force `` if the danger could be avoided only '' by using it , but does not require a threatened person to try first to flee . In states with more restrictive self defense rules , deadly force is only an option if someone subjected to an attack ca n't escape with complete safety . In Florida and elsewhere , however , even if someone is an aggressor , he can regain the right to use self defense if he withdraws from the confrontation that he initiated .

Thus , a major challenge for the prosecution team in the Martin case may be the version of events that Zimmerman offers . In his account , the first face-to-face encounter with Trayvon Martin was occasioned when the teenager approached him and said , `` You got a problem ? '' as Zimmerman was walking away .

It is imperative for the state to emphasize evidence that the defendant is not justified in his killing and discredit or explain all contradictory evidence . Witness statements will have to be parsed with great care , especially where they appear to support Zimmerman 's version of events . The prosecution should also make sure that the defendant can not introduce into the minds of the jurors something that is so off-putting that it gives rise to doubt about the propriety of the defendant 's intentions and actions .

Even though the state has a lode of evidence , including vitally important 911 tapes that can offer a unique window into the motives of Zimmerman on that fateful night , it needs to be mindful of the narrative of fear that will be told by the defense counsel . -LRB- The Florida gated community has seen a number of crimes , Zimmerman was acting as a good citizen by being a neighborhood watch member , Martin is a powerfully built teenager , etc. -RRB- The defense will no doubt also exploit any lack of thoroughness in the police and forensic investigation as a bungled rush to judgment that can unsettle the minds of jurors who might otherwise be horrified by the shooting .

To convict Zimmerman , a jury would have to find that there is no reasonable view of the evidence that would justify his lethal actions . Of course , the state 's star witness , Trayvon Martin , is unavailable to them .

The opinions expressed in this commentary are solely those of Eugene O'Donnell .

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Eugene O'Donnell : Prosecutor needs to see if Zimmerman can be proven guilty

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O'Donnell : No American should ever be prosecuted for a crime because of demands of crowds

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He says prosecutors should vigorously pursue cases when justice demands it

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O'Donnell : Major challenge for prosecution would be disproving Zimmerman 's story